According to the examinations made by the inventors of the present invention, with respect to the apparatus for mobile communication system such as a mobile phone, the following techniques are known.
For example, in a mobile phone, a PA in which a semiconductor amplifier device such as a MOSFET or a GaAs-MESFET is used in an output section of the transmission side is built in addition to a base band LSI (hereinafter, referred to as BBLSI) as a control circuit device having a function to control the transmitting and receiving of signal and a radio frequency IC (hereinafter, referred to as RFIC) as a radio frequency circuit. The PA amplifies up to the required output voltage for communications and then outputs the output voltage.